College Calculus: Level I Review of Functions

In this video, we are going to do a quick review of functions. First, we will see what the function is and what the domain and range of function are. We will see how to determine whether the y is a function of x or not using the Vertical Line Test. Then we will see some examples of functions and their roughly drawn sketches. After that we are going to talk about some other descriptive terms of functions like Odd and Even functions or Increasing and Decreasing functions. At the end, we are going to review types of functions and do some examples.

if x=0, then the sqrt of zero is zero, which would be included in the function.

1 answer

Last reply by: Taylor WrightWed Aug 7, 2013 1:49 AM

Post by Maureen Dempseyon March 27, 2013

hi what is the difference between exponenial and power function....don't they both involve an exponent? She didn't really clarify how they are different. thanks for a great tutoria otherwise.

0 answers

Post by Eun Jee Kangon October 9, 2012

I can't continue the lesson after odd and even examples. Please check it out. i don't know what problem is.

0 answers

Post by Jacob Mackon August 8, 2012

y = x^2 + 1 would be a function but y^2 = x + 1 is not. To see this algebraically instead of geometrically we can plug a number in for x for the first equation, say, 2, so 2 squared is four + 1 is 5. We have exactly one value of x domain we get one output of y in the equation. Thus, 2^2 + 1 = 5 is a function. Plugging in 3 for the second equation we see it is not a function: y^2 = 3 + so y can be = 2 or -2, therefore there are two outputs from the range y of the equation.

0 answers

Post by Jacob Mackon August 8, 2012

In general, any equation can yield a corresponding graph and any graph can be represented by a corresponding equation. Like y = x^2 yields the familiar parabola.

For y = log(x) we can break it apart to be y = f(x) = 1n(x) + x and then move on to solve geometrically.

0 answers

Post by Jason Mannionon October 4, 2011

Video works fine for me so far. Hope to get a better handle on Calculus now!

0 answers

Post by Marsha Tayloron January 23, 2011

These videos are a great for learning math or for review.

0 answers

Post by NICK FOSTERon January 20, 2011

no iam sorry about that comment everything is ok the videos play and are amazing!!keep up the good job

Review of Functions

These are review
topics from algebra and pre-calculus  it would be good to just
briefly brush up on these things!

As you go through
calculus, it will be important to use the correct terminology for
the various terms associated with functions  clear mathematical
communication is important!

Review of Functions

Simplify tanx cscx

y = tanx cscx

= [sinx/cosx] [1/sinx]

= [1/cosx] = secx

Simplify cscx cosx

y = cscx cosx

= [1/sinx] cosx

= [cosx/sinx]

=cotx

Simplify [4x sinx/(x2 cos3x)]

y = [4x sinx/(x2 cos3x)]

= [4x/(x2)] [sinx/cos3x]

and cannot be combined because their arguments differ. The arguments must be the same to rewrite trig functions. 0Find the domain and range of

sin and cos are periodic functions, meaning the outputs will repeat once the input is shifted over a full period. The unit circle is a good way to see this. No matter what real numbers we put into the function, the same pattern repeats. The output never exceeds 1 or goes below -1

Domain (), Range [-1, 1] 0Find the domain and range of

This is similar to the previous problem, but it's a bit trickier because it introduces zero into the denominator. The function is said to be undefined where the input results in a zero in the denominator. For this function, we won't have any problems when the denominator is not zero. So the domain involves any x when is not zero. is zero at any multiple of , including zero. Now, we're dividing by really tiny numbers (approaching zero). An integer divided by a very small number, is a very large number. Domain is all real numbers, but cannot equal any multiple of . where n is any integer. Range 0Graph

This is very similar to the regular cos graph, except that its period is changed, or quished." Its usual period of is now .

0Graph

This is similar to the regular sin graph, but it is shifted UP by one unit. 0Graph

is very different from . Radians are used unless otherwise specified. By convention, the variable typically implies use of degrees).

has a period of , meaning that going units in x in either direction will return the same result

etc...

so this is the same graph as

0Graph

The number out front here determines the amplitude. In this case, it's 3. So from minimum to maximum, this graph will cover 6 units total. Multiplying the x here by 2 changes the period from to .

0Graph

The positive 4 there moves the graph over 4 units to the left. The -1 in that location means the graph is shifted down 1. This is the same graph as the previous problem, but shifted down 1 and 4 to the left.

0Simplify

This is equivalent to , which would give an exponent of , or

0Rewrite

0Rewrite

0Combine the exponents of

0Combine the exponents of

0Simplify

0Simplify

0Solve for x,

0Solve for x,

0Prove

ADVANCED NOTE: This is the exponential expression of the trig identity

0Given , find

0Solve for x,

0Simplify

0Solve for x,

x = 1 0Solve for y,

0Solve for x,

0Solve for x,

0Simplify

Here, the base is irrelevant. 0Solve for ,

The second solution, -9, would be outside of the domain of . For , x must be greater than 0. So

0Prove

Let and

0Find the roots of

0Find the roots of

Two identical roots, 0Find the asymptote(s) of

We already found the roots on the previous problems. The asymptote is where the function is undefined. Here, it's when the denominator is equal to zero. We know that the denominator is equal to zero when . The function goes to positive infinity when approaching the root () from the positive direction. The function also goes to positive infinity when approaching the root from the negative direction (The degree of the polynomial in the denominator is even). 0Graph

We already determined the asymptote behavior, what about the edge behavior? As x gets very large and positve, y approaches zero. As x gets very large and negative, y also approaches zero from the positive side.

0Find the asymptote(s) of

The function is undefined at x = 0. The function goes to positive infinity when approaching zero from the positive direction. The function goes to negative infinity when approaching zero from the negative direction (Remember, the polynomial in the denominator is of odd degree). 0Find the asymptote(s) of

. The function is undefined when . when

There are an infinite number of asymptotes for and those asymptotes are at odd integer multiples of 0Graph

This is similar to the graph of , but it is shifted 5 to the left.

0Graph

Even degree polynomial in the denominator. As x gets very large in either direction, y approaches zero. There are two asymptotes here, -2 and 2. That gives us 4 different cases for asymptotic behavior. Approaching -2 from the left, Approaching -2 from the right, approaching 2 from the left, and approaching 2 from the right. Plugging in values to test for these cases.

0Graph

Asymptotes are at same locations as previous problem, so we can find the asymptote behavior in a similar fashion

0Graph

Remember the properties of . Domain , , and is an increasing function. As x gets larger, f(x) approaches zero and f(x) has an asymptote at x = 1.

*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.

Answer

Review of Functions

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.